Crimping tools for securing metal connectors to electrical conductors are well known and widely used. Known crimping tools generally include a first handle, a second handle, a mechanical linkage located intermediate the first and second handles to allow pivotal movement therebetween, and an attached working head comprised of two pivotally connected jaws. A first die, or die groove, is defined in one jaw, and a second die, or die groove, is defined in the second jaw in alignment with the first die. When the handles are opened, or spread apart, the mechanical linkage forces the jaws apart so that a connector can be inserted into an aperture defined between the dies, or die grooves.
After a conductor is introduced into the connector, and is properly aligned therewith, the ends of the handles remote from the dies are manually operated. The crimping pressure exerted by the dies, or die grooves, upon the connector radially indents same, and mechanically, and electrically, joins the connector to the conductor. At the completion of each crimping operation, the handles are swung apart, to an open position, so that the connector and conductor can be removed from the dies, or die grooves.
During crimping operations, a connector is placed within the crimping dies, and the operator, or installer, closes the handle inwardly. When the crimping operation occurs, compressive loads are developed at the mechanical linkage interface with the tool handles. The tool handles are sturdy enough to withstand such compressive loads, and a properly crimped connector results upon full closure of the handles.
Representative crimping tools are shown in U.S. Pat. No. 3,330,148, granted Jul. 11, 1967 to Elmer H. Hornung, and U.S. Pat. No. 3,120,772, granted Feb. 11, 1964, to James L. Mixon.
Additionally, the Hornung patent recognized that the components of the crimping tool must be manufactured and assembled within close tolerances, so that the tool can perform satisfactorily for extended periods of time, under field conditions. To achieve these desirable goals, Hornung provided an adjusting screw (43) that manipulated the position of toggle arm (37) that joined the handles, and dies, together. Gage notch (45) and gage edge (44) provided a visual indication to the operator of the tool that the tool was in proper alignment. When misalignment was detected, adjusting screw (43) was manipulated to adjust linkage (37) so that gage indicators (44, 45) were brought into the desired relationship.
Another crimping tool that relies upon a visual indicator to alert the operator to diminution of effectiveness of the tool is disclosed in U.S. Pat. No. 5,279,140, granted to Mark W. Blake et al, and assigned to Burndy Corp., the assignee of the present invention. U.S. Pat. No. 5,279,140 discloses a crimping tool (10) including a working head (12) and a pair of handles (14). The working head is made of metal, and comprises pivotally connected jaws (16, 17) joined by straps, or plates (18), on opposite sides thereof. Die cavities (20, 21) are defined between the cooperating surfaces of the jaws.
The handles are operably connected to each other by strengthening links (23) and a bolt (26). The handles are made of an impact resistant polymer plastic. Cooperating markings, or indicia (54, 58), are defined on strengthening link (23) and on one handle. When excessive misalignment occurs, as reflected by indicia (54, 58) visible to the operator, the handles may be replaced, and proper alignment re-established.
Furthermore, as noted previously, the mechanical linkages of known crimping tools are subjected to compressive loading during crimping operations. Sturdy metal handles, or polymer composite materials, as disclosed in U.S. Pat. No. 5,279,140, are designed to accept such loads so that the tools function satisfactorily.
However, when the handles of known crimping tools are pivoted outwardly to the end of their opening stroke, the possibility of excessive loading exits. If impact loads, or large static loads, are applied to the tool in the opened orientation, such as may occur when the tool is dropped from a considerable height, significant tensile loads are created at the mechanical linkage interface. The tool handles are considerably stronger in compression, than in tension, and the significant tensile loads adversely influence the structural integrity and operational characteristics of the crimping tool.